Traffic and Highway Engineering
5th Edition
ISBN: 9781305156241
Author: Garber, Nicholas J.
Publisher: Cengage Learning
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Question
Chapter 6, Problem 25P
To determine
The percentage reductions in space mean speed at the vicinity of the work zone, if the flow upstream is
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The capacity of a highway is suddenly reduced to 60% of its normal capacity due toclosure of certain lanes in a work zone. If the Greenshields model describes the relationship between speed and density on the highway, the jam density of the highway is112 veh/mi, and the mean free speed is 64.5 mi/h, determine by what percentage thespace mean speed at the vicinity of the work zone will be reduced if the flow upstream is 80% of the capacity of the highway.
The relationship between flow and density on a four-lane highway (two lanes per direction) is
known to follow GreenShiled's model, with a free flow speed of 100 km/h and a jam density of
80 veh/km/lane. One of the two lanes of the EB direction will be closed for an entire month for
maintenance. The traffic demand for the highway on a typical weekday is shown in the table below.
a) What is the maximum length of the queue upstream of the bottleneck during both the
morning and afternoon peak hours?
b) At what time will the morning and afternoon queues be dissipated?
c) Draw the shock wave diagram (for the entire day) showing shock wave speeds, critical
times, and distances.
Time
7:00 AM - 9:00 AM
9:00 AM 3:00 PM
3:00 PM 7:00 PM
7:00 PM–11:00 PM
11:00 PM 7:00 AM
Average Demand (vph)
3000
1500
3200
1200
400
A two-lane, one-way, rural freeway segment is being designed to service a demand volume of 4,000 vehicles per hour. The PHF is expected to be 0.95. If the combination of trucks, buses, and recreational vehicles is represented by a heavy vehicle adjustment of 0.85, what is the flow rate (pcphpl)? Provide your answer to the nearest integer.
Chapter 6 Solutions
Traffic and Highway Engineering
Ch. 6 - Prob. 1PCh. 6 - Prob. 2PCh. 6 - Prob. 3PCh. 6 - Prob. 4PCh. 6 - Prob. 5PCh. 6 - Prob. 6PCh. 6 - Prob. 7PCh. 6 - Prob. 8PCh. 6 - Prob. 9PCh. 6 - Prob. 10P
Ch. 6 - Prob. 11PCh. 6 - Prob. 12PCh. 6 - Prob. 13PCh. 6 - Prob. 14PCh. 6 - Prob. 15PCh. 6 - Prob. 16PCh. 6 - Prob. 17PCh. 6 - Prob. 18PCh. 6 - Prob. 19PCh. 6 - Prob. 20PCh. 6 - Prob. 21PCh. 6 - Prob. 22PCh. 6 - Prob. 23PCh. 6 - Prob. 24PCh. 6 - Prob. 25PCh. 6 - The arrival times of vehicles at the ticket gate...Ch. 6 - Prob. 27P
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Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, civil-engineering and related others by exploring similar questions and additional content below.Similar questions
- Traffic flow on a four-lane (one direction) freeway can be described by the Greenshields model. Two lanes of the four lanes on a section of this freeway will have to be closed to undertake an emergency bridge repair that is expected to take 2 hr. The mean free speed of the highway is 60 mi/h and the jam density is 140 veh/mi/ln. If it is estimated that the demand flow on the highway during the emergency repairs is 80% of the capacity, using the deterministic approach, determine: (a) The maximum queue length that will be formed (b) The total delay(c) The number of vehicles that will be affected by the incident(d) The average individual delayarrow_forwardA freeway with two northbound lanes is shut down because of an accident. At the time of theaccident, the traffic flow rate is 1200 vehicles per hour per lane and the flow remains at this level.The capacity of the freeway is 2200 vehicles per hour per lane when not impacted by an accident.The freeway is shut down completely for 20 minutes after the accident and then one lane is openfor 20 minutes and finally both lanes are opened (40 minutes after the accident). What is theaverage delay per vehicle resulting from the accident (assuming D/D/1 queuing)?arrow_forwardA traffic engineer has set up a one-mile study segment of a corridor. He measures the speed of 10 vehicles. Calculate the space mean speed and time mean speed of these vehicles. If the space mean speed occurs at an optimal flow with a density of 75 veh/mi, what is the capacity of this roadway?arrow_forward
- freeway with two northbound lanes is shut down because of an accident. At the time of the accident, the traffic flow rate is 1200 vehicles per hour per lane and the flow remains at this level. The capacity of the freeway is 2200 vehicles per hour per lane when not impacted by an accident. The freeway is shut down completely for 20 minutes after the accident; then one lane is opened 20 minutes after accident; and finally both lanes are opened 40 minutes after the accident. What is the total delay resulting from the accident (assuming D/D/1 queuing)?arrow_forwardQUESTION 10 A two-lane, one-way, rural freeway segment is being designed to service a demand volume of 4,000 vehicles per hour. The PHF is expected to be 0.95. If the combination of trucks, buses, and recreational vehicles is represented by a heavy vehicle adjustment of 0.85, what is the flow rate (pcphpl)? Provide your answer to the nearest integer.arrow_forwardExample 1 The adjusted demand flow (v₂) of 1,800 pc/h/In is traveling on a freeway with a free-flow speed (FFS) of 65 mi/h. For this condition, what is the expected speed?arrow_forward
- 7.11 A four-lane highway has a free-flow speed of 100 km/h and the flow-density relationship shown below. (1) Plot the relationship between flow and density. From this equation, determine (2) the flow capacity of the highway. Calculate (3) the jam density and (4) the speed at capacity and determine (5) the level of service when the highway is at capacity. q=100k-0.5k² lutionchin shown below.arrow_forwarddue to closure of certain lanes of a highway, the capacity is reduced to 75% of its normal capacity. If in normal capacity the jam density of the highway is 103 veh/km, and the free flow speed is 58 kph, determine what would be the maximum flow if the flow is limited to 85% of its current state.arrow_forwardTraffic flow on a section of a 2 lane road can be described by the Greenshields model with a mean free speed of 80 kph and jam density of 95 veh/km/lane. At the time when a flow was 90% of the capacity of the road, a large dump truck loaded with heavy industrial machinery from an adjacent construction site joins the traffic stream and travels at a speed of 20kph for a length of 6.60 km along the upgrade before turning off onto a dump site. Due to the relatively high flow in the opposite direction, it is impossible for any car to pass the truck. Find how many vehicles will be in the platoon behind the truck by the time the truck leaves the road. Find also the shockwave speed created by the truck.arrow_forward
- Traffic flow on a section of a two-lane highway can be described by the Greenshields model, with a mean free speed of 54 mi/h and a jam density of 146 veh/mi/In. At the time when the flow was 90 percent of the capacity of the highway, a large dump truck loaded with heavy Industrial machinery from an adjacent construction site joins the traffic stream and travels at a speed of 18 mi/h for a length of 3.5 mi along the upgrade before turning off onto a dump site. Due to the relatively high flow In the opposite direction, it is impossible for any car to pass the truck. Determine how many vehicles will be in the platoon behind the truck by the time the truck leaves the highway.arrow_forwardTwo lanes of the four lanes on a highway section have to be closed to undertake an emergency bridge repair that is expected to take 120minutes hr. The highway's mean free speed is 90km/h, and the jam density is 140 veh/km/ln. If it is estimated that the demand flow on the highway during the emergency repairs is 80% of the capacity (max flow), using the deterministic approach, determine: 1. The maximum queue length that will be formed.2. The number of vehicles that will be affected by the incident.3. The average individual delay.arrow_forwardQuestion 1. The free mean speed on a roadway is found to be 80 kmph. Under stopped condition, the average spacing between the vehicles is 6.9 m. What is the capacity flow?arrow_forward
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